Conventionally, in optical communications using optical fibers, an optical module such as a surface-emitting laser (for example, VCSEL: Vertical Cavity Surface Emitting Laser) having a light emitting element has been used.
In such an optical module, an optical module component called optical receptacle is used. The optical receptacle couples light including communication information emitted from a light emitting element with an end surface of an optical fiber, and thus achieves optical transmission through the optical fiber.
Conventionally, in the optical module, for the purpose of adjusting the light output or stabilizing the output characteristics of an light emitting element against temperature variation, various techniques for monitoring (observing) the light (intensity and light amount) emitted from a light emitting element have been proposed.
For example, PTL 1, which has been made by the present inventor, discloses an invention directed to an optical module including a lens array which is an example of optical receptacles. In the invention disclosed in PTL 1, laser light emitted from a light emitting element is first incident on a first lens surface, and then reflected by a reflecting surface toward an optical fiber side, and thereafter, separated into coupling light directed to the optical fiber and monitoring light by a reflection-and-transmission layer disposed in a recess of a lens array main body. Then, after sequentially passing through a prism disposed in the recess, a filler, and the lens array main body, the coupling light is output from a second lens surface toward an end surface of an optical fiber. On the other hand, after passing through the lens array main body, the monitoring light is output from a third lens surface toward a light-receiving element.